(1) Field of the Invention
This invention relates to a temperature pattern measurement device for obtaining a surface temperature distribution of an object.
(2) Description of the Prior Art
Generally, the prior art temperature pattern measuring method has widely employed an infrared ray system which two-dimensionally receives, by means of an infrared ray detection element, the optical energy from infrared rays emitted from an object comprising the target to be measured, and which scans the two-dimensional picture so that a temperature pattern on the surface of the object corresponding to the picture may be dispalyed, for example, graphically by means of a cathode-ray tube (CRT). The prior art measuring method using the infrared ray system, however, is inadequate for an object which changes its temperature because two or more seconds are required for scanning one picture. The received infrared rays which contain the temperature information are apt to be affected by the atmosphere surrounding the light propagation path so as to lower the system sensitivity and accuracy due to the presence of vapor or dust. It is also actually impossible to avoid the influence of the surrounding atmosphere by the use of an image guide, because the light intensity attenuation is greater inside the infrared ray zone within the image guide. Furthermore, since the actual minimum visual field for measurement is greater than a 10 to 20 centimeter-angle, the temperature pattern in a minimum area cannot be measured. Hence, the prior art infrared ray system measurement cannot be applied to the measurement of the temperature pattern of an object, such as metal slab, during the continuous casting process at a steel mill, or an electrically seamed steel pipe being welded, or an object surrounded by a bad atmosphere rich in vapor or dust and having rapid temperature changes. More particularly, it is quite impossible for the prior art systems to measure the temperature pattern at a minimum area, such as at the hot portion of the edge of an electrically seamed steel pipe.
On the other hand, a two-color thermometer, which is applied as the fundamental technique of the present invention, receives two predetermined wavelength components in the visible region which are emitted from an object, thereby measuring the object surface temperature by non-contact techniques. The two color thermometer can measure a typical temperature within the visual field but not the temperature pattern. Under these circumstances, iron manufacturing and steel manufacturing processes often need to measure the temperature pattern, but the above-noted temperature pattern measuring methods cannot easily meet such a requirement.